Physiology concepts standard

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Questions and Answers

Physiology is primarily the study of:

Function (correct)

Appearance

Shape

Structure

Which of the following is NOT a main speciality of physiology:

Cell physiology

Pathophysiology

Atomic physiology (correct)

Special physiology

Which of the following is NOT a principal life process?

Differentiation

Movement

Adaptation (correct)

Responsiveness

Which of the following is a recognized level of physiological organization?

Chemical/molecular level Signup and view all the answers

What is the term of the process by which a nearly stable environment is maintained in the body?

Homeostasis Signup and view all the answers

Which term describes the regulatory mechanism that controls or adjusts activities of many systems simultaneously?

Extrinsic regulation Signup and view all the answers

A feedback loop contains all of the following components EXCEPT:

Stimulator Signup and view all the answers

What is the primary mechanism providing long-term control maintaining constant internal conditions?

Negative feedback Signup and view all the answers

Which of the following demonstrates a positive feedback loop?

Childbirth Signup and view all the answers

Communication and integration is essential to maintaining homeostasis, relying on ______________ signals.

chemical and electrical Signup and view all the answers

Which of the following is NOT a basic mechanism of cell-to-cell communication?

Intracellular communication Signup and view all the answers

All of the following are principal components of cells, EXCEPT:

Exclusions Signup and view all the answers

The plasma membrane is a gatekeeper regulating the passage of substances into and out of the cell described by the ______________ model.

fluid mosaic Signup and view all the answers

Which of the following is NOT a key function of the plasma membrane in human cells?

Regulation of gene transfer Signup and view all the answers

Which type of membrane protein is bound to the inner or outer surface of the membrane?

Peripheral Signup and view all the answers

Membrane proteins serve various specialized functions including each of the following, EXCEPT:

Effectors Signup and view all the answers

A membrane through which any substance can pass without difficulty is:

Freely permeable Signup and view all the answers

When passage across the selectively permeable cell membrane requires energy expenditure, it is known as:

Active Signup and view all the answers

Transport processes can be categorized by each of the following mechanisms, EXCEPT:

Osmosis Signup and view all the answers

The process of diffusion tends to ________________ a concentration gradient.

eliminate Signup and view all the answers

Which of the following is NOT a principal characteristic of osmosis?

It tends to produce an electrochemical gradient Signup and view all the answers

Which types of cells employ electrical impulses?

Neurons and muscle Signup and view all the answers

The generation of electrical impulses requires the presence of an ____________ membrane.

excitable Signup and view all the answers

Membranes generate electrical impulses through the distribution of:

Ions Signup and view all the answers

A positively charged ion is called a:

Cation Signup and view all the answers

Unlike (or opposite) charges ______________ each other.

attract Signup and view all the answers

When there is a difference between the number of positive and negative charges across a cell membrane, this is commonly termed a ______________ difference.

potential Signup and view all the answers

Which of the following is a principal ion involved in neural impulse generation?

Sodium Signup and view all the answers

Potassium (K+) ions tend to move out of the cell through open potassium channels, creating a:

Negative potential difference Signup and view all the answers

Because the _______________ concentration of sodium (Na+) ions is relatively high, sodium (Na+) ions tend to move into the cell.

extracellular Signup and view all the answers

At rest, the cell membrane is much more permeable to potassium than sodium, generating a potential difference of:

-70 mV Signup and view all the answers

The potential difference across the cell membrane sets up a:

Electrical gradient Signup and view all the answers

If the cell membrane were freely permeable to a particular ion, but impermeable to all other ions, that ion would continue to leave the cell until the electrical gradient was as strong as the chemical gradient - this is called the _______________.

equilibrium potential Signup and view all the answers

The equilibrium potential for sodium (Na+) is:

+60 mV Signup and view all the answers

Ion channels permit the movement of ions in and out of the cell and are principally regulated by:

Voltage or chemicals Signup and view all the answers

Voltage-gated ion channels can be in each of the following states, EXCEPT:

Open, and incapable of closing (tetanized) Signup and view all the answers

Any shift from the resting potential towards 0 mV is called a:

Depolarization Signup and view all the answers

The following are typical physiological membrane potentials, EXCEPT:

Electrode potential Signup and view all the answers

Graded potentials are local changes in membrane potential that:

Can be depolarizing or hyperpolarizing Signup and view all the answers

A ____________________ is a brief, stereotyped (all-or-none) change in membrane potential in the positive direction during excitation of a neuron.

action potential Signup and view all the answers

Study Notes

Physiology

The study of how living organisms function
Focuses on the functions of the body systems and how these systems interact

Specialties of Physiology

Cell physiology: focuses on the functions of individual cells
Special physiology: explores the functions of specific organs
Pathophysiology: studies the physiological changes that occur during disease

Principal Life Processes

Responsiveness: the ability to detect and respond to changes in the environment
Movement: includes the motion of the whole body, individual organs, single cells, and even organelles inside cells.
Growth: an increase in size and complexity, due to an increase in the number of cells
Differentiation: the process by which unspecialized cells become specialized into particular types of cells.
Reproduction: the formation of new cells or new organisms
Metabolism: all chemical reactions taking place in the body

Levels of Physiological Organization

Chemical/molecular level: atoms combine to form molecules
Cellular level: molecules form organelles
Tissue level: similar cells that work together to perform a specific function
Organ level: two or more tissues that work together
Organ System level: a group of organs that work together to perform a common function
Organism level: all the organ systems of the body working cooperatively

Homeostasis

Maintenance of a relatively stable internal environment
Essential for cell survival and proper function
Examples: regulating body temperature, blood pressure, and blood glucose levels

Regulatory Mechanisms

Intrinsic regulation: occurs within a specific organ
Extrinsic regulation: results from the activities of the nervous or endocrine systems that control or adjust the activities of many systems simultaneously

Feedback Loops

Control mechanisms that help maintain homeostasis
Components:
- Receptor: detects changes in environment, sending a message to the control center
- Control center: receives, processes, and integrates information from the receptor
- Effector: receives commands from the control center and carries out a response
Negative feedback: reduces the initial change
- Most important mechanism for maintaining homeostasis, examples: regulation of body temperature, blood pressure, and blood glucose levels
Positive feedback: exaggerates the initial change
- Usually used for short-term processes, examples: childbirth, blood clotting, and the generation of nerve impulses

Communication and Integration

Homeostasis relies on chemical (hormones) and electrical (nerve impulses) signals
Communication essential for survival and function

Cell-to-Cell Communication

Direct cytoplasmic transfer: occurs between cells that are connected by gap junctions
Local chemical communication: occurs between cells that are close to each other
Long-distance communication: occurs between cells that are far apart
- Involves the use of hormones, neurotransmitters, neurohormones

Components of Cells

Plasma membrane: the outer boundary of the cell
- Fluid mosaic model: membrane consists of a phospholipid bilayer with embedded proteins
Cytosol: the fluid inside the cell
Organelles: specialized structures within the cell
- Inclusions: non-living substances that may be present in the cytoplasm, examples: glycogen granules, lipid droplets, and pigment granules

Plasma Membrane

Functions:
- Physical isolation: separates the cell’s internal environment from the external environment
- Regulation of exchange with the environment: controls the movement of substances into and out of the cell
- Sensitivity to the environment: receives signals from the environment
- Structural support: helps maintain the shape of the cell
Types of membrane proteins:
- Integral proteins: embedded in the phospholipid bilayer, many act as channels, receptors, carriers, or enzymes
- Peripheral proteins: bound to the inner or outer surface of the membrane

Membrane Transport

Passive transport: does not require energy
- Types:
  - Diffusion: movement of a substance from an area of high concentration to an area of low concentration
  - Osmosis: diffusion of water across a selectively permeable membrane
Active transport: requires energy (ATP)
- Types:
  - Carrier mediated transport: substances bind to membrane proteins, and the proteins facilitate their movement across the membrane
  - Vesicular transport: substances are transported in membrane-bound vesicles

Diffusion

Characteristics:
- Movement from a region of high concentration to a region of low concentration
- Movement down the concentration gradient
- Depends on the size of the particles
- Requires no energy input
- Important for the movement of oxygen, carbon dioxide, nutrients, and waste products

Osmosis

Characteristics:
- Movement of water molecules across a selectively permeable membrane
- Movement from an area of high water concentration to an area of low water concentration
- Will move towards the solution which has the higher concentration of solutes
- Influenced by the solute concentration
- Important for maintaining cell volume and fluid balance

Electrical Impulses

Cells that use electrical impulses are excitable cells
- Types: neurons and muscle cells
Electrical impulses generated by changes in the distribution of ions across the cell membrane
Key ions: potassium (K+) and sodium (Na+)

Membrane Potential

Resting potential: the potential difference across the cell membrane when the cell is at rest
- Typically around -70 mV
Depolarization: a shift in the membrane potential towards 0 mV
- Can be caused by the opening of sodium channels
Repolarization: a return of the membrane potential to the resting potential
- Caused by the closing of sodium channels and the opening of potassium channels
Hyperpolarization: a shift in the membrane potential below the resting potential
- Caused by the continued opening of potassium channels
Equilibrium potential: the membrane potential at which the electrical gradient is equal and opposite to the chemical gradient
- The movement of ions across the membrane stops
- For example, the equilibrium potential for sodium (Na+) is +60 mV

Ion Channels

Types:
- Voltage-gated: open in response to changes in membrane potential
- Ligand-gated: open in response to the binding of a ligand to the channel protein, examples: neurotransmitters, hormones
- Mechanically-gated: open in response to a mechanical stimulus
States:
- Closed: not allowing ions to pass through
- Open: allowing ions to pass through
- Inactivated: closed and incapable of opening

Graded Potentials

Local changes in membrane potential
- Can be depolarizing or hyperpolarizing
- The change in membrane potential is proportional to the strength of the stimulus
- Decrease in intensity with distance from the site of the stimulus

Action Potentials

Brief, stereotyped (all-or-none) changes in membrane potential
- Occur when the membrane potential reaches a threshold value
- The amplitude of the action potential is always the same
- The duration of the action potential is also always the same
- Important for the transmission of nerve impulses and muscle contractions

Steps Involved in Generating an Action Potential

Resting potential: the neuron is polarized, with a negative charge inside the cell and a positive charge outside the cell
Depolarization: the membrane potential becomes less negative, due to the opening of sodium channels
Repolarization: the membrane potential becomes more negative, due to the closing of sodium channels and the opening of potassium channels
Hyperpolarization: the membrane potential becomes more negative than the resting potential, due to the continued opening of potassium channels
Return to resting potential: the membrane potential returns to the resting potential

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Test your knowledge on the essential aspects of physiology, focusing on how living organisms function and the various specialties within the field. Explore key life processes such as responsiveness, movement, growth, and more. Ideal for students studying basic human physiology.